--- a/src/HOLCF/IOA/meta_theory/CompoTraces.thy	Sat Nov 03 01:38:39 2001 +0100
+++ b/src/HOLCF/IOA/meta_theory/CompoTraces.thy	Sat Nov 03 01:39:17 2001 +0100
@@ -21,7 +21,7 @@
        nil => nil
     | x##xs => 
       (case x of 
-        Undef => UU
+        UU => UU
       | Def y => 
          (if y:act A then 
              (if y:act B then